Medical punches are used in certain surgical procedures to cut tissue. For example, a blood vessel is cut using a medical punch, and surgical scalpels and/or scissors are first used to form an incision in the vessel. Typically, the medical punch includes an anvil which is first inserted into the incision. Then, a tube of the medical punch extends, and a cutting edge of the tube slides along the anvil, thus shearing the vessel tissue. Finally, the anvil and cutting edge of the tube of the medical punch are withdrawn from the incision following completion of such a cut.
The cutting edge of the distal end of the tube in conventional medical punches commonly includes a flat cutting edge having effectively no shearing angle and requiring the entire cutting edge to cut simultaneously into the vessel tissue during the cutting operation. Because the conventional medical punch accomplishes cutting of tissue by shearing, and effects this shearing by sliding a cutting edge past the anvil, the vessel tissue does not remain centralized and may shift slightly during the cut, and the cut thus produced is not always clean and accurate because some fraying may result. Moreover, because the vessel tissue is commonly very durable and the cutting edge of the tube is flat, the entire peripheral surface of the cut is effected at the same time, requiring a lot of hand pressure to successfully manipulate the medical punch through the tissue-cutting procedure. Additionally, because the vessel tissue does not remain centralized and shifts during the cutting operation, the vessel tissue has a tendency to gather to one side or the other of the anvil of the device. This often causes the device to become jammed with vessel tissue.
There is a need for an improved medical punch which does not have a tendency to jam, which can be used to obtain a very clean and accurate cut without any fraying, and which can be operated without excessive hand pressure. Further, with advances in other anastomosis-related technologies, there is a need for an improved medical punch that can be used on a blood vessel that is pressurized by blood flowing through it without having to place a clamp on the vessel to divert the blood away from the punched site.
In conventional medical punches, the anvil must be forced into the initial incision made by scalpels and/or scissors. This can result in problems if the incision is not large enough. Inserting the anvil into this small incision can result in tearing of the vessel tissue, and in difficulty operating the punch if the anvil must be awkwardly forced into position. The anvil can be more easily inserted if the incision is too large, but the procedure may result in leakage around the edges of the opening that is made by the punch and that is smaller than the insertion incision.
Medical punches disclosed in the prior art sometimes include a sharp tip that is pressed against the vessel wall to both make the incision and to then insert the anvil into the incision in one step. This avoids the need for a separate instrument to make the initial incision. However, this again involves difficulty in forcing the wider anvil base through a small hole in the vessel. This can result in tearing of vessel tissue and awkwardness in manipulation while trying to insert the anvil through the vessel wall. Putting a great deal of pressure on the punch to force the sharp tip into the vessel may involve the risk of forcing the tip too far and puncturing the opposite side of the vessel wall. Additionally, such a sharp-tipped device must be inserted into the body cavity and into the vicinity of the appropriate vessel without accidentally puncturing any other tissue in the path. A smaller anvil base could be incorporated into a one-step punch to allow for easier insertion. However, such a smaller anvil may not cut a sufficiently large hole as may not hold the intima layer of the vessel wall sufficiently firmly against the media layer after insertion into the vessel, resulting in a potentially dangerous separation of tissue layers within the vessel.
It is necessary in some surgical procedures to get an accurate measurement of the vessel wall thickness before using a medical punch to make an aperture in the vessel wall. Currently, epi-aortic scans allow for this form of measurement, but involve introduction of additional medical devices with concomitant risks to the patient.
There is a need for an improved medical punch that minimizes the problems of vessel wall tearing and difficult manipulation during anvil insertion, while still having a sufficient anvil width to clamp tissue layers within a vessel wall against separation during formation of an aperture in the vessel wall. There is a need for a one-step punch with little risk of puncturing or traumatizing unintended tissues. There is also a need for a device for measuring the thickness of a vessel wall easily and accurately during the tissue punching procedure, and without the need for introduction of a separate measuring device into the patient.